Combined packaged power semiconductor device

ABSTRACT

A combined packaged power semiconductor device includes flipped top source low-side MOSFET electrically connected to top surface of a die paddle, first metal interconnection plate connecting between bottom drain of a high-side MOSFET or top source of a flipped high-side MOSFET to bottom drain of the low-side MOSFET, and second metal interconnection plate stacked on top of the high-side MOSFET chip. The high-side, low-side MOSFET and the IC controller can be packaged three-dimensionally reducing the overall size of semiconductor devices and can maximize the chip&#39;s size within a package of the same size and improves the performance of the semiconductor devices. The top source of flipped low-side MOSFET is connected to the top surface of the die paddle and thus is grounded through the exposed bottom surface of die paddle, which simplifies the shape of exposed bottom surface of the die paddle and maximizes the area to facilitate heat dissipation.

PRIORITY CLAIM

This application is a continuation and claims the priority benefit of aU.S. patent application Ser. No. 13/077,720 filed Mar. 31, 2011, theentire disclosures of which are incorporated herein by reference.

TECHNOLOGY FIELD

This invention relates to a power semiconductor device, especially to apackage structure that combines semiconductor chips and other componentsin the same power semiconductor device.

BACKGROUND

Currently, a typical power semiconductor device usually combines metaloxide semiconductor field effect transistors (MOSFETs) and an integratedcircuit (IC) controller in one package to reduce number of peripheraldevices and improve the utilization efficiency of power supplies andother components. For a double diffused metal oxide semiconductor fieldeffect transistor (DMOSFET) having a source on its top surface, the topsource of the chip usually is connected to an exposed die paddle of alead frame and thus is grounded.

To achieve the above said package structure, the chip has to be flippedand attached to the lead frame die paddle, which will face somedifficulties, such as the optimization of the size and simplification ofthe shape of the exposed die paddle of lead frame, the achievement ofthe connection between the chip source and the die paddle to optimizeheat dissipation, and the achievement of a good interconnection betweenthe gate on top of the chip and the IC controller for such a flip chipconfiguration.

A specific existing semiconductor device package as shown in FIG. 1 ismade according to the circuit diagram in FIG. 2, which contains a P-typehigh-side (HS) MOSFET, a N-type low-side (LS) MOSFET and an ICcontroller that are installed on one lead frame. The installation spaceof the package limits the size of the HS MOSFET, LS MOSFET and ICcontroller, which have a great impact on the improvement of performanceof power semiconductor device.

However, in the above package structure, electrodes on top surface ofthe LS MOSFET connect to the HS MOSFET, the IC controller or externalcomponents directly through bonding wires, which may be connected to thesame pin. Therefore, it is difficult to install a flip chip to connectthe source on its top surface with the die paddle, and it is impossibleto make the exposed die paddle as electrode ground and to improve theheat dissipation effect.

SUMMARY

This invention provides a combined packaged, or co-packaged, powersemiconductor device including semiconductor chips, such as HS and LSMOSFETs with top source, top gate and bottom drain, and an IC controllerin one package. The overall size of co-packaged power semiconductordevice is reduced, and the size of the semiconductor chips is enlargedwith the same package size, which effectively improve the performance ofsemiconductor device. The electrical connection between the source ofthe flip chip with the die paddle is achieved and the exposed area atthe bottom surface of the die paddle is grounded and maximized thatimproves heat dissipation.

This invention provides methods of combined packaging for the abovepower semiconductor device. The method is started with a lead frameincluding a die paddle and a plurality of pins that are separated andelectrically insulated from the die paddle. The LS MOSFET chip isflipped and stacked on the die paddle, forming an electrical connectionbetween the LS source and a top surface of the die paddle, thus the LSsource is grounded through the exposed bottom surface of the die paddle.A first metal interconnection plate is attached on the drain of the LSMOSFET. HS MOSFET is either directly attached or flipped first and thenattached on the first metal interconnection plate, forming electricalconnections between a drain of HS MOSFET or a source of flipped HSMOSFET and the drain of the LS MOSFET through the first metalinterconnection plate.

A second metal interconnection plate is attached on and electricallyconnected to the source of HS MOSFET or the drain of flipped HS MOSFET.The IC controller is also stacked on the die paddle. The IC controllerincludes a plurality of electrodes and electrical connections betweenthe pins of the lead frame, the electrodes on the IC controller and theelectrodes of HS and LS MOSFETs are formed through bonding wires.

In a preferred embodiment, the lead frame pins include a LS gate pinincluding an outer portion and an inner portion. A matching gap is madeon said die paddle at the corresponding position to that of innerportion to separate the LS gate pin from the die paddle. The gate of theflipped LS MOSFET is attached on the inner portion and thus forms anelectrical connection with the LS gate pin. The inner portion of the LSgate pin includes a half etched area, which is filled with plasticmaterial in packaging process The half etched area is also formed on aside of the die paddle corresponding to the inner portion with a widthmatching to that of the inner portion and is also filled with plasticmaterial in packaging process to enhance the connection strength in thedevice and maximizes the exposed bottom surface of the die paddle. TheIC controller is electrically connected to the LS gate pin's outerportion through bonding wires.

In another preferred embodiment, the combined packaged powersemiconductor device also includes a second interposer. The gate offlipped LS MOSFET is attached and electrically connected to a conductivetop surface of the second interposer. The bottom surface of the secondinterposer is attached to and electrically insulated from die paddle.The source of the flipped LS MOSFET is electrically connected to the diepaddle through a thick conductive adhesive.

In an improved structure of this embodiment, a second groove is formedin a top portion of the die paddle corresponding to the position of thegate of the LS MOSFET. The second interposer is placed in the secondgroove and is electrically insulated from the die paddle. The secondinterposer can be a conductive metal plate, which is attached on the diepaddle or in the second groove through a non-conductive adhesive at itsbottom surface. Alternatively, the second interposer maybe include aconductive metal upper layer and an insulated lower layer with thebottom surface of the insulated lower layer attached on the die paddlein the second groove through either conductive or non-conductiveadhesive. The IC controller is electrically connected to the top surfaceof the second interposer, thus forming electrical connection with gateof the flipped LS MOSFET.

In another preferred embodiment, the IC controller is attached to andelectrically insulated from the die paddle. The flipped LS MOSFET isattached to and covers a portion at top surface of the IC controller,thus electrical connection between some electrodes on the IC controllerand the gate and a portion of source of the LS MOSFET are formed, whicheliminates the utilization of bonding wires and simplifies the packagingprocess. Furthermore, the IC controller is also packagedthree-dimensionally in this structure, thus reducing the overallthickness of power semiconductor device. The remaining portion of thesources of LS MOSFET is electrically connected to the die paddle througha thick conductive adhesive.

In an improved structure of this embodiment, a chip groove is formed ona top portion of the die paddle. The IC controller is then placed in thechip groove and is electrically insulated from the die paddle. Thecombined packaged power semiconductor device also includes the firstinterposer. The gate of the flipped HS MOSFET is electrically connectedto the conductive top surface of the first interposer.

The bottom surface of the first interposer is attached on andelectrically insulated from the first metal interconnection plate. Thesource of the HS MOSFET is electrically connected to the first metalconnectors through a thick conductive adhesive.

In an improved structure of this embodiment, a first groove is formed ona top portion of the first metal interconnection plate corresponding tothe position of the gate of the HS MOSFET for housing the firstinterposer that is electrically insulated from the first metalinterconnection plate. The first interposer can be a conductive metalplate, which is attached on the first metal interconnection plate or inthe first groove through a non-conductive adhesive at its bottomsurface. Alternatively, the first interposer may include a conductivemetal upper layer and an insulated lower layer with the bottom surfaceof the insulated lower layer attached on the first metal interconnectionplate or in the first groove through either a conductive or anon-conductive adhesive. The IC controller is electrically connected tothe top surface of the first interposer, forming electrical connectionwith the gate of the flipped HS MOSFET. Source and gate of the HS MOSFETor bottom drain of flipped HS MOSFET are electrically connected to theIC controller by bonding wires.

The lead frame pins also include switch pins that are electricallyconnected with the first metal interconnection plate. The IC controlleris connected to the switch pins through bonding wires, thus formingelectrical connections with the first metal interconnection plate. Thelead frame pins also includes HS source pins electrically connected tothe source of the HS MOSFET through the second metal interconnectionplate. The lead frame pins also includes HS drain pins electricallyconnected to the drain of the flipped HS MOSFET through the second metalinterconnection plates.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic diagram of an existing co-package of a powersemiconductor device;

FIG. 2 is a circuit diagram for a co-package of a HS P-type MOSFET, a LSN-type MOSFET and an IC controller;

FIG. 3 is a circuit diagram for a co-package of the N-type HS and LSMOSFETs and the IC controller;

FIG. 4 is a three-dimensional diagram illustrating a co-package of powersemiconductor device corresponding to the circuit diagram of FIG. 2according to a first embodiment of the present invention;

FIG. 5 is three-dimensional diagram illustrating a co-package of powersemiconductor device corresponding to the circuit diagram of FIG. 3;

FIG. 6 is a cross-sectional view along line A-A of the co-package ofpower semiconductor device of FIG. 4 or FIG. 5;

FIG. 7 is a cross-sectional view along line C-C of the co-package ofpower semiconductor device of FIG. 5, FIG. 10 or FIG. 15;

FIG. 8 is a three-dimensional diagram illustrating the co-package ofpower semiconductor device of FIG. 4 or FIG. 5 from its backside;

FIG. 9 is a three-dimensional diagram illustrating a co-package of powersemiconductor device corresponding to circuit diagram of FIG. 2according to a second embodiment of the present invention;

FIG. 10 is a three-dimensional diagram illustrating a co-package ofpower semiconductor device of corresponding to circuit diagram of FIG.3;

FIG. 11 is a cross-sectional view along line B-B of the co-package ofpower semiconductor device of FIG. 9 or FIG. 10;

FIG. 12 is an alternative cross-sectional view along line B-B of theco-package of power semiconductor device of FIG. 9 or FIG. 10;

FIG. 13 is a three-dimensional diagram illustrating the co-package ofpower semiconductor device of FIG. 9, FIG. 10, FIG. 14 or FIG. 15 fromits back side;

FIG. 14 is a three-dimensional diagram illustrating a co-package ofpower semiconductor device corresponding to circuit diagram of FIG. 2according to a third embodiment of the present invention;

FIG. 15 is a three-dimensional diagram illustrating a co-package ofpower semiconductor device corresponding to circuit diagram of FIG. 3;

FIG. 16 is a cross-sectional view along line D-D of the co-package ofpower semiconductor device of FIG. 14 or FIG. 15;

FIG. 17 is an alternative cross-sectional view along line D-D of theco-package of power semiconductor device of FIG. 14 or FIG. 15;

FIG. 18 is an alternative cross-sectional view along line C-C of theco-package of power semiconductor device of FIG. 5, FIG. 10 or FIG. 15.

SPECIFIC EMBODIMENTS

Some preferred embodiments of this invention according to FIG. 4 to FIG.18 are described below in detail for better understanding the technicalsolution and useful effects of this invention.

In the following embodiments, an IC controller is connected to HS and LSMOSFETs, all of which are co-packaged in the same package forming apower semiconductor device. It should be noted that these specificdescriptions and examples are not for the purpose of limiting the scopeof this invention.

As shown in FIG. 2, a LS MOSFET is an N-type MOSFET, while the HS MOSFETis a P-type MOSFET. Both of the HS and LS MOSFETs have bottom drain, topsource and top gate electrodes. In this configuration, the LS MOSFET isflipped. Gate G1 of HS MOSFET and gate G2 of LS MOSFET are bothconnected to an IC controller. The source S1 of HS MOSFET is connectedto a power access terminal Vin, with its drain D1 connected to drain D2of LS MOSFET at a switch terminal Lx connecting to the IC controller,while source S2 of LS MOSFET connects to the ground.

As shown in FIG. 3, both of the HS and LS MOSFETs are N-type MOSFETshaving bottom drain, top source and top gate electrodes. In thisconfiguration, both HS and LS MOSFETs are flip chips. A gate G3 of HSMOSFET and a gate G2 of LS MOSFET are both connected to the ICcontroller. The drain D3 of HS MOSFET is connected with a power accessterminal Vin, with its source S3 connected with drain D2 of LS MOSFET ata switch terminal Lx that connects to the IC controller, while source S2of LS MOSFET connects to the ground.

A first embodiment of the present invention is described in FIG. 2, FIG.4 and FIG. 6. FIG. 4 is a three-dimensional diagram of a co-package of apower semiconductor device, while FIG. 6 is a cross-sectional view alongline A-A of the power semiconductor device of FIG. 4. As shown in FIG.4, P-type HS MOSFET 30, N-type LS MOSFET 20 and an IC controller 40 areco-packed in one package of the power semiconductor device.

The power semiconductor device package includes a lead frame containinga die paddle 100 and a plurality of pins separated from the die paddle100. The plurality of pins include HS source pin 72, LS gate pin 71,switch pin 74 and a plurality of control pins 75. The die paddle 100should be large enough to arrange the LS MOSFET 20 and the IC controller40 side-by-side in the same plane.

As shown in FIG. 6, the LS gate pin 71 includes an outer portion 712 atan outer end and an inner portion 711 at an inner end. A matching gap101 is formed on a side of the die paddle 100 at the correspondingposition to that of inner portion 711 of the LS gate pin 71 to separatethe LS gate pin 71 from the die paddle 100.

The flipped LS MOSFET 20 is attached onto the die paddle 100 through aconductive adhesive 91, with the main part of this LS MOSFET 20 beingcovered on one end of top surface of the die paddle 100, forming anelectrical connection between the source 22 and the die paddle 100,while its gate 21 is correspondingly covered on the inner portion 711 ofthe LS gate pin 71, forming an electrical connection between the gate 21and the pin 71 through conductive adhesive 91.

A half etched area 713 at the bottom surface of the inner portion 711 isfilled with plastic material in packaging process to enhance theconnection strength between the inner portion 711 and the LS MOSFET 20.Another half etched area 104 is also formed at a side of the die paddle100 corresponding to half etched area 713 of the inner portion 711. Thishalf etched area 104 is also filled with plastic material in packagingto simplify the shape of exposed bottom surface of the die paddle 100.

The outer portion 712 of the LS gate pin 71 and the bottom surface ofdie paddle 100, except the half etched area 104, will expose outside thebottom surface of the power semiconductor device after being packaged,as shown in FIG. 8. Source 22 of the LS MOSFET 20 is grounded (Gnd) asshown in FIG. 2 by the connection of the bottom surface of die paddle100 to ground. In addition, the exposed bottom surface of die paddle 100improves heat dissipation performance.

The IC controller 40 is attached on the other end of top surface of thedie paddle 100. The IC controller 40 has a plurality of electrodes onits top surface, which are connected through boning wires to controlpins 75 and the outer portion 712 of the LS gate pins 71.

The first metal interconnection plate 51 (or other metal connects suchas metal connecting strips) is connected on top of the LS MOSFET 20through conductive adhesive 91, forming an electrical connection betweenthe drain 23 of the LS MOSFET 20 and the bottom surface of the firstmetal interconnection plate 51, and further forming an electricalconnection with the switch pin 74 through the first metalinterconnection plate 51 as shown in FIG. 7.

The HS MOSFET 30 is attached on the first metal interconnection plate 51through conductive adhesive 91, forming an electrically connectionbetween its drain 33 and top surface of the first metal interconnectionplate 51, thus forming an electrical connection between the HS drain 33and the LS drain 23 and switch pin 74 through the said first metalinterconnection plate 51. The switch pin 74 is electrically connected toelectrode of the IC controller 40 by bonding wires 80, forming a circuitconnection at switch end Lx, as shown in FIG. 2. Gate 31 and source 32of the HS MOSFET 30 are also electrically connected to the IC controller40 by bonding wires 80.

The second metal interconnection plate 52 is attached on top of the HSMOSFET 30 through conductive adhesive 91, forming an electricalconnection between source 32 of the HS MOSFET 30 and the second metalinterconnection plate 52, and further forming an electrical connectionto the HS source pin 72, which forms a power access terminal Vin asshown in FIG. 2.

An alternative configuration of a co-package of a power semiconductordevice is described in FIG. 3, FIG. 5, FIG. 6 and FIG. 7. FIG. 5 is athree-dimensional diagram of a power semiconductor device package, whileFIG. 6 and FIG. 7 are cross-sectional views along line A-A and line C-Crespectively of the power semiconductor device package FIG. 5. Accordingto the circuit diagram as shown in FIG. 3, this power semiconductordevice package includes the IC controller 40 and both N-type HS and LSMOSFETs.

The structure of the lead frame that includes a die paddle 100 and aplurality of pins and the connecting configuration of the IC controller40 and LS MOSFET 20 on the die paddle 100 are same as that describedabove in FIG. 4.

Typically, as shown in FIG. 5, FIG. 6 and FIG. 8, the flipped LS MOSFET20 is connected on the die paddle 100, with its source 22 beingelectrically connected with the die paddle 100, and its top gate 21being electrically connected with the inner portion 711 of the LS gatepin 71. The first metal interconnection plates 51 stacks on top of theLS MOSFET chip 20, forming an electrical connection between drain 23 ofthe LS MOSFET 20 and the switch pin 74. The die paddle 100 is alsoconnected to the IC controller 40, forming an electrical connectionbetween IC controller 40 and the control pins 75, outer portion 712 ofLS gate pin 71, and the switch pin 74 by bonding wires 80. The halfetched areas 104 and 713 are filled with plastic material in packagingprocess. All pins (including the outer portion 712 of LS gate pin 71)and area of bottom surface of die paddle 100, except the half etchedarea 104, expose from the bottom surface of the power semiconductordevice.

In this embodiment, the HS MOSFET 30 is an N-type MOSFET and is alsoflipped. The flipped HS MOSFET 30 is stacked on the first metalinterconnection plate 51, forming an electrical connection between thesource 32 of the HS MOSFET 30 and the first metal interconnection plate51 through conductive adhesive 91. HS source 32 forms electricalconnection with LS drain 23 through the first metal interconnectionplate 51, and further forms electrical connection with the IC controller40 through the switch pin 74, forming the switch terminal Lx as shown inFIG. 3.

The gate 31 of the flipped HS MOSFET 30 is connected on the first metalinterconnection plate 51 through the first interposer 61 and formselectrical connection between this gate 31 and the IC controller 40through the first interposer 61.

Specifically, the first groove 511 is formed on a top portion of thefirst metal interconnection plate 51 with a shape and size conformingwith the first interposer 61 and corresponding to the position of gate31 of the flipped HS MOSFET 30.

The first interposer 61 is insulated from the first metalinterconnection plate 51 and is electrically connected with gate 31 ofthe HS MOSFET 30. By way of example, the first interposer 61 can be aconductive metal plate, with its bottom surface being attached to thefirst metal connector 51 in the first groove 511 through non-conductiveadhesive 92. Alternatively, the first interposer 61 may include a topconductive metal layer and a bottom insulator layer, such as a glasslayer, in which the bottom surface of this bottom insulator layer can beconnected with the first metal interconnection plate 51 in the firstgroove 511 through conductive or nonconductive adhesive.

Top surface of the first interposer 61 is electrically connected withthe gate 31 of the HS MOSFET 30 through conductive adhesive 91. The topsurface of the first interposer 61 is not completely covered by the gate31 and the boding wire 80 is formed between the IC controller 40 and thefirst interposer 61 achieving an electrical connection between ICcontroller 40 and the gate 31 of the HS MOSFET 30.

The second metal interconnection plate 52 is attached on top of the HSMOSFET 30 through conductive adhesive 91, forming an electricalconnection between drain 33 of the HS MOSFET 30 and the second metalinterconnection plate 52, and further forming an electrical connectionwith the HS drain pin 73 through the second metal interconnection plate52, forming a power access terminal Vin as shown in FIG. 3. The ICcontroller 40 is also electrically connected with the drain 33 throughthe bonding wire 80.

A second embodiment of the present invention is described in FIG. 2,FIG. 9 and FIG. 11, in which, FIG. 9 is three-dimensional diagram of apower semiconductor device co-package, and FIG. 11 is a cross-sectionalview of the power semiconductor device co-package of FIG. 9 along lineB-B. According to the circuit diagram as shown in FIG. 2, a P-type HSMOSFET 30, an N-type LS MOSFET 20 and an IC controller 40 areco-packaged in this power semiconductor device.

Similar to the structure of the power semiconductor devise as describedabove in FIG. 4, the IC controller 40 is placed at one end of the diepaddle 100 of leads frame, and the flipped LS MOSFET 20, the first metalconnector 51, HS MOSFET 30 and the second metal connector 52 are placedat the other end of the die paddle 100. The top surface and bottomsurface of the first metal interconnection plate 51 are electricallyconnected with drain 23 and 33 of the HS and LS MOSFETs 20 and 30respectively, and further connected the switch pin 74. Bonding wires 80form an electrical connection between the switch pin 74 and the ICcontroller 40, forming the switch terminal Lx as shown in FIG. 2. Thesecond metal interconnection plate 52 is electrically connected withsource 32 of the HS MOSFET 30 and the HS source pin 72, forming thepower input terminal Vin as shown in FIG. 2. The IC controller 40 isalso electrically connected to the gate 31 and the source 32 of the HSMOSFET 30, and to the control pins 75 through bonding wires 80.

In this embodiment, a second groove 102 is formed by a half etching atop portion of the die paddle 100 corresponding to the position of gate21 of the flipped LS MOSFET 20. A second interposer 62 is formed in thesecond groove 102, and is electrically insulated from the die paddle100.

Specifically, similar to the first interposer 61, the second interposer62 can be a conductive metal plate, with its bottom surface beingattached to the die paddle 100 in the second groove 102 through anon-conductive adhesive 92. Alternatively, the second interposer 62 mayinclude a top conductive metal layer and a bottom glass layer or otherinsulator layers, with the bottom insulator layer connecting to the diepaddle 100 through either a conductive or a nonconductive adhesive.

The gate 21 of the flipped LS MOSFET 20 can be electrically connected tothe conductive top surface of the second interposer 62 throughconductive adhesive 91. The second interposer 62 is not completelycovered by the gate 21, so that a bonding wire 80 is formed between theIC controller 40 and the second interposer 62, achieving an electricalconnection between IC controller 40 and the gate 21 of the LS MOSFET 20.At the same time, source 22 of the LS MOSFET 20 can be electricallyconnected with the top surface of the die paddle 100 through conductiveadhesive 91, and grounded as shown in FIG. 2. As the second interposer62 in this embodiment is placed in the second groove 102 of the diepaddle 100, the LS gate pin 71 in FIG. 4 can be replaced with a controlpin 75. In this embodiment the bottom surface of the die paddle 100completely exposes outside the power semiconductor device after itsbeing packaged as shown in FIG. 13, achieving a larger heat dissipatingarea.

An alternative configuration of the power semiconductor device isdescribed in FIG. 3, FIG. 7, FIG. 10 and FIG. 11. FIG. 10 is athree-dimensional diagram of the power semiconductor device co-package,while FIG. 7 and FIG. 11 are cross-sectional views of the powersemiconductor device co-package in FIG. 10 along line C-C and line B-Brespectively. According to the circuit diagram as shown in FIG. 3, thispower semiconductor device co-package includes the IC controller 40 andboth N-type HS and LS MOSFETs 20 and 30.

In this embodiment, the IC controller 40 is positioned on one end of thedie paddle 100 of leads frame, and flipped LS MOSFET 20, the first metalinterconnection plate 51, flipped HS MOSFET 30 and the second metalinterconnection plate 52 are positioned on the other end of the diepaddle 100.

Similar as above, a second interposer 62 is placed on and iselectrically insulated from the die paddle 100 in the second groove 102.The flipped LS MOSFET chip 20 is stacked on the die paddle 100 and thesecond interposer 62, forming electrical connection between source 22 ofthe LS MOSFET 20 and the die paddle 100 through the conductive adhesive91, with its gate 21 being electrically connected with the conductivetop surface of the second interposer 62. The first metal interconnectionplate 51 is stacked on the LS MOSFET 20, forming an electricalconnection between drain 23 of the LS MOSFET chip 20 and the switch pin74.

The first groove 511 is formed on a top portion of the first metalinterconnection 51 with the first interposer 61 is attached on the firstmetal interconnection plate 51 in the first groove 511. Gate 31 of theflipped N-type HS MOSFET 30 is electrically connected with theconductive top surface of the first interposer 61. At the same time,source 32 of the HS MOSFET 30 is electrically connected with the topsurface of the first metal interconnection plate 51, thereforeelectrically connected to the drain 23 of the LS MOSFET 20, and theswitch pin 74, forming a switch terminal Lx, as shown in FIG. 3. Thesecond metal interconnection plate 52 located above the drain 33 of theHS MOSFET 30 is electrically connected to the HS drain pin 73, forming apower access terminal Vin as shown in FIG. 3. The IC controller 40 iselectrically connected to the control pins 75, top conductive surface ofthe first and second interposers 61 and 62, the switch pin 74, and drain33 of the HS MOSFET 30 through the bonding wires 80.

As shown in FIG. 13, the whole bottom surface of die paddle 100 in thisembodiment can be exposed completely outside the power semi-conductordevice after being packaged as a ground, as such the source 22 of LSMOSFET 20 is also grounded as shown in FIG. 3. The exposed bottomsurface of die paddle 100 improves heat dissipation.

FIG. 12 is an alternative structure of FIG. 11. As shown in FIG. 12, theflipped LS MOSFET 20 is stacked on top of the die paddle 100 throughconductive adhesive 91 forming an electrical connection between thesource 22 of LS MOSFET 20 and the die paddle 100. The second interposer62 is stacked on top and insulated from the die paddle 100 with the topsurface of second interposer 62 electrically connected to the gate 21through conductive adhesive. The conductive adhesive 91 between the LSMOSFET 20 and the die paddle 100 is thick enough such that the topsurface of the conductive adhesive 91 between the LS MOSFET 20 and thedie paddle 100 and the top surface of the conductive adhesive betweenthe second interposer 62 and the LS MOSFET 20 are co-planar.

A third embodiment of the present invention is described in FIG. 2, FIG.14 and FIG. 16, in which, FIG. 14 is a three-dimensional diagram of thepower semiconductor device, and FIG. 16 is a cross-sectional view of thepower semiconductor device in FIG. 14 along line D-D. According to thecircuit diagram as shown in FIG. 2, P-type HS MOSFET 30, N-type LSMOSFET 20 and IC controller 40 are co-packaged.

In this embodiment, the flipped LS MOSFET 20, the first metalinterconnection plate 51, HS MOSFET 30, second metal interconnectionplate 52 are stacked on top each other on the die paddle 100 of the leadframe in a similar structure as described above in FIG. 4 and FIG. 9.Typically, top and bottom surfaces of the first metal interconnectionplate 51 are electrically connected with drain 23 and drain 33 of the HSand LS MOSFETs respectively, and further connected to the switch pin 74,forming the switch terminal Lx as shown in FIG. 2.

The second metal interconnection plate 52 is stacked on top of the HSMOSFET chip 30 and is electrically connected with its top source 32, andfurther connected to the HS source pin 72, forming the power inputterminal Vin as shown in FIG. 2.

In this embodiment, a chip groove 103 is formed by half etching area topportion of the die paddle 100. This chip groove 103 has a shape and sizeconforming to the shape and size of the IC controller 40, such that theIC controller 40 can be positioned in the chip groove 103 and isinsulated from the die paddle 100.

For example, a chip groove 103 of a depth of 4 μm can be formed by halfetching for an IC controller 40 with a height of 4 μm, making topsurface of the IC controller 40 located in the chip groove 103 at thesame level with the top surface of the die paddle 100. The flipped LSMOSFET 20 covers a portion of top surface of the IC controller 40, withits gate 21 and a portion of source 22 being directly electricallyconnected with some electrodes on top surface of the IC controller 40through conductive adhesive 91, which eliminates the utilization of thebonding wire and simplifies the packaging process. The remaining sources22 of the LS MOSFET 20 is electrically connected with top surfaces ofthe die paddle 100 excluding the chip groove 103 through a conductiveadhesive 91. The bottom surface of the die paddle 100 can be exposedcompletely outside the power semi-conductor device after being packaged,as shown in FIG. 13, resulting the remaining of source 22 of the LSMOSFET 20 being grounded as shown in FIG. 2. The exposed bottom surfaceof die paddle 100 also improves heat dissipation. The IC controller 40is also electrically connected with the control pin 75, the switch pin74, gate 31 and source 32 of the HS MOSFET 30 by the bonding wires.

In the above embodiments, the IC controller 40 is arranged on the sameplane with the LS MOSFET 20 on the top surface of the die paddle 100. Inthis embodiment, the IC controller 40 is placed in the chip groove 103of the die paddle 100 and the LS MOSFET 20 is stacked on top of the ICcontroller 40, forming a three-dimensional package structure. Thus, inthis embodiment, the LS MOSFET 20 and the IC controller 40 can be placedon different planes in the die paddle 100 with the same area, as sucheach of them can enlarge their own area to improve the performance ofthe power semi-conductor device.

An alternative configuration is described in FIG. 3, FIG. 7, FIG. 15 andFIG. 16, in which, FIG. 15 is a three-dimensional diagram of the powersemiconductor device, while FIG. 7 and FIG. 15 are cross-sectional viewsof the power semiconductor device in FIG. 15 along line C-C and line D-Drespectively. According to the circuit diagram as shown in FIG. 3, thispower semiconductor device is a co-package of the IC controller 40 andN-type HS and LS MOSFETs. Similar to the above configuration, the ICcontroller 40 is placed in the chip groove 103, which is formed by halfetching on a top portion of die paddle 100, and is electricallyinsulated from the die paddle 100.

The flipped MOSFET 20 covers a portion of top surface of IC controller40, making direct connection between its gate 21 and source 22 with someelectrodes on top surface of IC controller 40. The remaining source 22of the LS MOSFET 20 is electrically connected with top surfaces of thedie paddle 100 excluding the chip groove 103 area. The bottom surface ofthe die paddle 100 can be exposed completely outside the powersemi-conductor device after being packaged, as shown in FIG. 13, as suchthe remaining portion of source 22 of the LS MOSFET 20 is grounded asshown in FIG. 3.

In this embodiment, the flipped LS MOSFET 20, the first metalinterconnection plate 51, the flipped HS MOSFET chip 30, and the secondmetal interconnection plate 52 is stacked on top each other in a similarorder as described above. Specifically, the first metal interconnectionplate 51 is stacked on the LS MOSFET 20, forming an electricalconnection between drain 23 of the LS MOSFET 20 and the switch pin 74. Aportion of the top surface of the first metal interconnection plate 51is half-etched to form the first groove 511, and a first interposer 61is placed in the first groove 511.

The gate 31 of the flipped N-type HS MOSFET 30 is electrically connectedto the conductive top surface of the first interposer 61. The source 32of the HS MOSFET 30 is electrically connected to the top surface of thefirst metal interconnection plate 51, thus electrically connected to thedrain 23 of the LS MOSFET 20, and switch pin 74, forming a switchterminal Lx, as shown in FIG. 3.

The drain 33 of the HS MOSFET 30 is electrically connected to the HSdrain pin 73 through the second metal interconnection plate 52, forminga power access terminal Vin as shown in FIG. 3. The IC controller 40 iselectrically connected to control pins 75, switch pin 74, top surface ofthe first interposer 61, and drain 33 of the HS MOSFET 30 throughbonding wires 80.

FIG. 17 is an alternative structure of FIG. 16. As shown in FIG. 17, theIC controller 40 is stacked on and insulated from the die paddle 100without forming a groove on top portion of the die paddle. The flippedLS MOSFET 20 covers a portion of top surface of IC controller 40, withits gate 21 and a portion of source 22 being electrically connected tosome electrodes on top surface of IC controller 40 by a conductiveadhesive. The remaining of source 22 of the LS MOSFET 20 is electricallyconnected to the die paddle 100 through a thick conductive adhesive 91,which is thick enough such that the top surface of the thick conductiveadhesive between the remaining source 22 and the die paddle 100 and thetop surface of the conductive adhesive between the portion of source 22and the IC controller are co-planar.

In addition, FIG. 18 is an alternative structure of FIG. 7. In FIG. 7,the first groove 511 is formed in a top portion of the first metalinterconnection plate 51 for housing the first interposer 61. In FIG.18, the flipped HS MOSFET 30 is stacked on the first metalinterconnection plate 51 and the first interposer 61 is directly stackedon and insulated from the first metal interconnection plate 51, with thetop surface of the first interposer 61 being electrically connected withthe gate 31 through conductive adhesive. Source 32 of the HS MOSFET 30is electrically connected with the first metal interconnection plate 51through a thick conductive adhesive 91, which is thick enough such thatthe top surface of the thick conductive adhesive between the source 32and the first metal interconnection plate 51 and the top surface of theconductive adhesive between the gate 31 and the first metalinterconnection plate 51 are co-planar.

The combined packaged power semiconductor device in this inventionincludes the LS MOSFET, the first metal interconnection plate, the HSMOSFET and the second metal interconnection plate stacked on top eachother on a die paddle, achieving a three-dimensional package thatreduces the overall size of the power semi-conductor device.

Although the contents of this invention have been described in detail inthe above said preferred embodiments, it should be recognized that theabove description shall not be considered as a limitation on thisinvention. After reading the above description by technical personnel inthis field, a number of modifications and replacements for thisinvention will be obvious. Therefore, the scope of protection for thisinvention shall be limited by the attached claims.

The invention claimed is:
 1. A combined packaged power semiconductordevice, comprising: a high-side (HS) MOSFET and a low-side (LS) MOSFET,each of said HS and LS MOSFETs comprising a bottom drain, a top gate anda top source; a lead frame comprising a die paddle and a plurality ofpins separated and electrically insulated from said die paddle, whereinsaid LS MOSFET is flipped and stacked on said die paddle forming anelectrical connection between said LS source and a top surface of saiddie paddle, as such said LS source is electrically connected to anexposed bottom surface of said die paddle; a first metal interconnectionplate stacked on said drain of said LS MOSFET, wherein said HS MOSFETdirectly stacked or flipped first and then stacked on said first metalinterconnection plate, forming an electrical connection between said HSdrain or flipped HS source and said LS drain through said first metalinterconnection plate; a second metal interconnection plate stacked andelectrically connected to said source of said HS MOSFET or said drain ofsaid flipped HS MOSFET; an integrated circuit (IC) controller stacked onsaid die paddle, said IC controller comprising a plurality ofelectrodes, wherein electrical connections between said pins, saidelectrodes on said IC controller and electrodes of HS and LS MOSFETs areformed; an interposer wherein said gate of flipped LS MOSFET iselectrically connected to a conductive top surface of said interposerand a bottom surface of said interposer is stacked on and electricallyinsulated from said die paddle; and a second groove formed by halfetching a top portion of the die paddle corresponding to the position ofa gate of the flipped LS MOSFET with a second interposer formed in thesecond groove while electrically insulated from the die paddle.
 2. Thecombined packaged power semiconductor device of claim 1, wherein saidsource of said LS MOSFET is electrically connected to said die paddlethrough a thick conductive adhesive, wherein said thick conductiveadhesive is thick enough such that a top surface of said conductiveadhesive between said LS MOSFET and said die paddle and a top surface ofa conductive adhesive between said second interposer and said LS MOSFETare co-planar.
 3. The combined packaged power semiconductor device ofclaim 1, wherein a groove is formed at a top surface of said die paddlecorresponding to a position of said gate of said LS MOSFET and whereinsaid interposer is placed in said groove and is electrically insulatedfrom said die paddle.
 4. The combined packaged power semiconductordevice of claim 1, wherein said second interposer is a conductive metalplate with its bottom surface being connected on said die paddle or insaid second groove through a non-conductive adhesive.
 5. The combinedpackaged power semiconductor device of claim 1, wherein said interposercomprises a conductive metal upper layer and an insulated lower layer,wherein a bottom surface of said insulated lower layer is connected onsaid die paddle or in said groove through an adhesive.
 6. The combinedpackaged power semiconductor device of claim 1, wherein said ICcontroller is electrically connected with a top surface of saidinterposer, forming an electrical connection with said gate of saidflipped LS MOSFET.